The present invention relates generally to modular integrated accessory mounting assemblies for combat weapons. More specifically, the present invention relates to an accessory mounting assembly, which includes an actuator that is incorporated into the accessory mount in a manner that provides adjustable spring tension to control the clamping force exerted by the actuator against the firearm interface rail.
As the field of combat and commercial weaponry expands, numerous add-on enhancements have become available for attachment to standard firearms, thereby significantly upgrading the capability of the firearm. Of particular interest in the area of combat weapons is the well-known M16/M4 weapon system (M16 and M4 are trademarks of Colt Defense, Inc.). The M16 has been in service for a number of years and will continue to be a popular rifle both in U.S. and foreign militaries for the foreseeable future. Generally, the M16/M4 weapon 2, as depicted in FIG. 1, includes a lower receiver 4, upper receiver 6, butt stock 8, and barrel 10.
The newer models of the M16/M4 weapons further include a mil-std 1913 dovetail rail 12 extending along the top of the upper receiver. This integrated receiver rail 12 provides a convenient mounting point for many types of enhancement devices such as scopes and other sighting devices. However, space on the upper receiver rail 12 is limited, and many military personnel often have multiple sighting devices that are each tailored to perform in different combat situations. In addition, there are a variety of lighting devices, handgrips, etc. that could also be attached to the weapon for enhanced use of the weapon. The difficulty is that there is simply not enough space on the integrated rail provided on the upper receiver to accommodate all of the desired accessories. Accordingly, the increasing development and refinement of laser sights, infrared lighting, visible lighting, night vision, and specialized scopes and magnifiers, and other accessories continues to drive the need for versatile and reliable integration systems that include additional mil-std 1913 dovetail rails positioned above or around the barrel of the weapon that can support this important equipment and yet stand the test of rugged military use and abuse.
Responding to this need, the applicant has developed a modular integrated rail system (A.R.M.S.® S.I.R.® system) shown at FIG. 2, which has been well received by the military and has become popular with several branches of the military. The A.R.M.S. S.I.R. system is fully described in U.S. Pat. No. 6,490,822, the entire contents of which are incorporated herein by reference. These modular integrated rail systems for combat weapons 2 generally include an upper hand guard 14, a means 16 for securing the upper hand guard 14 to the weapon 2, a lower firearm accessory 18 (in most cases this is a lower hand guard), various optional rail segments, and in many cases, a sling swivel 20 for attaching a shoulder sling to carry the weapon 2.
The upper hand guard 14 is the main structural element of the system. The upper hand guard is 14 generally semi-cylindrical in shape and has a forward end and a rearward end and a mil-std 1913 dovetail rail 22 extending longitudinally between the forward end and the rearward end. The semi-cylindrical upper hand guard 14 further includes symmetrically opposing side walls that extend outwardly and downwardly from the dovetail rail and terminate in symmetrically opposing longitudinally extending mounting channels. The mounting channels are used to mount various accessories, such as a lower hand guard 18 or a grenade launcher, to the upper hand guard 14.
An interface means 16 is provided at the rearward end of the upper hand guard 14 to removably secure the upper hand guard 14 to the firearm 2. In the original S.I.R. system as shown in U.S. Pat. No. 6,490,822, the interface includes elongated sleeve that secures the upper hand guard 14 to the dovetail rail 12 on the top of the upper receiver 6 of the weapon 2 as well as a U-shaped yoke or clamp (not shown) that secured the upper hand guard 14 to the barrel nut of the weapon. In the other S.I.R. systems, the interface means 16 is a larger U-shaped yoke or clamp that secures the upper hand guard 14 exclusively to the barrel nut with the upper rail 22 sitting flush with the receiver rail 12.
As is well known in this area, field modification of weapon configurations is critical in combat situations. For example, it may be desired to swap the lower hand guard for a grenade launcher, which can be attached to the upper hand guard, or to add an optional rail segment for securing an added accessory. Similarly, there may be a desire to exchange various different sights or lighting accessories that are mounted on the various dovetail rails positioned around the weapon. In this regard standardized attachment assemblies have been developed to allow quick and easy removal and mounting of these devices relative to the dovetail rails.
Such an attachment device is disclosed in U.S. Pat. No. 5,276,988, issued on Jan. 11, 1994 to the present applicant, the contents of the '988 patent being incorporated herein by reference. Generally, the prior art attachment assemblies as shown at FIGS. 3A and 3B include a main body 24 having a lower portion that is configured to engage the dovetail rail 22 found on most modern combat weapons 2 and an upper portion 26 that can take on a variety of configurations depending on the accessory that is to be mounted thereon. The lower portion of the mounting assembly has a first engagement member 28 extending downwardly along one side thereof for engaging one side of the dovetail rail 22. Further, a boss formation 30 is provided adjacent the side of the main body to receive a clamping assembly 32 that is particularly suited to be releasably engaged with a second side of the dovetail rail 22 such that the clamping assembly cooperates with the first engagement member 28 to retain the modular mounting assembly in its installed position on the dovetail rail. The clamping assembly 32 generally includes a foot portion 32A with a cam surface 32B to engage the angulated surface of the dovetail rail 22, a post (not shown) extending upwardly through the boss formation 30 and a head portion 32C secured to the top end of the post and having actuator arm 32D to facilitate rotation of the foot portion 32A. The clamping assembly 32 further includes spring washers (not shown), which are captured between the bottom surface of the head portion 32C and the boss 30 (or a bushing within the boss) to provide a self-adjusting amount of spring tension as the clamping assembly 32 is rotated into engagement with the rail 22. These springs generally allow a limited, self-adjusted amount of biased vertical movement of the clamping foot 32A relative to the boss and the rail 22. Because the head portion 32C of the clamping assembly 32 is secured in a fixed position on the top end of the post, the spring are compressed by a fixed amount and therefore the force exerted by the foot 32A on the rail 22 was generally variable, but variable only within a certain range as determined by the initial spring tension. This small range of self-adjustment is critical in being able to accommodate the small dimensional variations in the dovetail rails of various equipment manufacturers.
Further, when such devices are employed with sighting accessories it is critical that the alignment of the device be repeatable and reliable after several removal and reinstallation cycles. If the camming force is too loose, the sight cannot be reinstalled with a high degree of accuracy. Similarly, if the camming force is too great, rotation of the cam foot can damage the rail creating a sloppy fit over time.
Finally, despite the benefits of a fixed, self-adjusting range of spring tension provided by the prior art device, in certain environments, there is still a perceived need to adjust the range of the spring tension, for example if rails have excessive wear there may be a need to slightly increase the initial spring tension. However, there is also a desire to prevent the user of the weapon from being able to adjust the tension without some type of restriction. Tighter is not better in these circumstances and over tightening can lead to damage to the rail of the weapon. Accordingly, while a need for adjustment may be accommodated, it should be provided in a manner that accommodates all of the environmental variables while still allowing the accessory mount to be ruggedly attached to the rail. There is thus a struggle between the benefits of a fixed mounting of the head portion 32C so as to provide a fixed, self-adjusting range of spring tension, and the perceived need to be able to adjust the range of the spring tension.
Accordingly, there is a perceived need for a modular mounting assembly that allows for the releasable mounting of various accessories onto the standard dovetail rail found on modern combat weapons and that can be reliably mounted onto a dovetail rail while including an actuator that includes the ability to adjust the spring tension that is exerted by the clamping foot.